Scientism is sometimes used to mean the acceptance of scientific theory and scientific methods as applicable in all fields of inquiry about the physical, natural world.

Scientism is sometimes used to refer to humanism and enlightenment values informed by science.

In this use of the word, scientism is "a scientific worldview that encompasses natural explanations for all phenomena, eschews supernatural and paranormal speculations, and embraces empiricism and reason as the twin pillars of a philosophy of life appropriate for an Age of Science." (Source: Michael Shermer, The Shamans of Scientism, Scientific American, 2002)

In this context, scientism is "a scientific worldview that encompasses natural explanations for all phenomena, eschews supernatural and paranormal speculations, and embraces empiricism and reason as the twin pillars of a philosophy of life appropriate for an Age of Science".

Scientism can be used as a pejorative term, typically to reject the assertion that the application of scientific understanding to all phenomena produces the predicted results and is, therefore, a reliable guide to policy.

Scientism is sometimes seen, when used in its pejorative sense, as being a term deployed from an anti-science standpoint, despite the fact that some of those who have used it in this way claim to be supporters of science who are merely proposing a less reductionist view of science.